The invention relates to novel, improved chromatography apparatus and methods consisting, as a minimum, of a chromatography column with a device for the axial compression of the column packing and/or of a pulsation-damping device and of an elution device.
In chromatographic separations of substances, especially in liquid chromatography, different pressures for the supply of eluent are necessary, depending on the desired flow rate, the viscosity of the eluent and the resistance to flow of, in particular, the separating column.
The operation of the varying operating pressures on the separating material in the column leads to stress thereon, so that the reproducibility of separation runs and the useful life of the column material may both deteriorate.
One method for solving this problem is disclosed in EP 0 271 378: the eluent provides, with its own pressure via a pressure-transmission arrangement and a device for compressing the separation material, the required backpressure which automatically adjusts to the operating state of the chromatography system. However, this compressive pressure collapses on switching the system off or on malfunctioning of the eluent pump. This results in the separating material in the column continuing to be mechanically stressed in a disadvantageous manner by consecutive compression and relaxation modes.
Another problem is that the operation of eluent pumps is not free of pulsations so that this too results in a mechanical stress on the complete system. The pulsation-damping devices employed for damping the pressure pulses operate only in a very narrow pressure range and thus lose efficacy under varying operating conditions. This is because the pressure of the eluent may vary within wide limits (about 10 to 250 bar).
It has now been found that improved chromatography systems can be provided in which a pressure composed of two components is applied to constructional elements such as a compression or a pulsation damping device. One of these two pressure components is proportional to the eluent pressure and the additional one is a constant minimum pressure.